It is often desirable to filter liquid to mechanically separate impurities from the liquid prior to use, that is, separating particulate material from the liquid. For example, in the case of fuel, such material can plug carburetor jets (or injection nozzles) and otherwise interfere with the operation of an internal combustion engine. Thus, fuel is typically filtered at the time it is dispensed at, for example, a service station, and is filtered again just prior to its use by a fuel filter associated with an internal combustion engine. While such filters adequately rid the fuel of particulate contaminants by mechanical filtering, such filters permit liquid contaminants to remain with the fuel. Example fuel filters include those by Cim-Tek® Filtration, which are available from Central Illinois Manufacturing Company of Bement, Ill.
A particularly troubling fuel contaminant is water, especially in alcohol-blended fuels. To provide background, alcohols are often added to fuel to, inter alia, boost octane, oxygenate, extend fuel supply, replace ethers, and reduce the impact of fossil fuels on the carbon cycle. Alcohol-blended fuels, however, react differently in the presence of water than alcohol-free fuels. That is, with alcohol-free fuels, water is heavier than the fuel and simply drops to the bottom of the fuel tank. Thus, as long as a proper maintenance protocol is followed, the water level in the fuel tank should not reach the level of an intake for a pump that draws the fuel from the fuel tank.
Unlike alcohol-free fuels, however, alcohol-blended fuels separate into two or more layers when exposed to excess water. The two or more layers typically include a denser, alcohol-water layer, and a less dense, fuel layer that is depleted in octane rating and alcohol soluble hydrocarbons. This separation is more commonly known as phase separation, or a phase separation condition. For example, ethanol-blended fuels (a common type of alcohol-blended fuel) contain ethanol, which is hygroscopic, meaning that it seeks out, and retains, water. At low water level concentrations, the ethanol is able to retain the water it has dissolved and remain associated with the fuel. That is, the fuel, water, and alcohol mixture remains stable and usable as a motor fuel. Once the water concentration exceeds a temperature-dependent threshold (e.g., the saturation point) for a given alcohol concentration, fuel-hydrocarbon content, and additives in the fuel (which typically contain alcohol as a major component), the ethanol and water phase separates from the fuel mixture. Under average temperature conditions in the United States, for example, water content of 0.3% to 0.5% by volume is typically a range within which phase separation occurs. The alcohol-water layer does not support combustion in a conventional gasoline engine, such as those in vehicles and generators, and, if introduced to the engine, may cause malfunction of internal combustion (e.g., engine stalling). Water may also damage expensive engine components, particularly fuel injectors.
To address phase separation concerns, developments have been made to treat fuel that has succumbed to phase separation prior to delivery from the storage tank to the engine. For example, commonly owned U.S. Pat. No. 8,439,984 to Kevin Dewayne Hughes, which was filed Apr. 14, 2009, discloses a method of treating a fuel to reverse phase separation. The method involves adding a liquid to the fuel to reverse the phase separation of the alcohol-water layer. Similarly, commonly owned U.S. Pat. Nos. 4,604,205; 4,623,560; 4,832,844; 4,539,107; 4,618,388; and 5,298,160, each to William R. Ayers et al., disclose filters, and filter media for use in a filter, that separate water and/or particulate material from a liquid to be purified, such as a hydrocarbon fuel.
Despite the forgoing techniques, a need remains for an improved, more effective, apparatus, such as a filter, that can detect excess water in fuel (indicating potential phase separation in a fuel, such as alcohol-blended fuels) and, in certain aspects, inhibiting delivery of such fuel to an engine, thereby mitigating damage to the engine. In at least one aspect, such a filter would be useful in fuel dispensers, such as those found at convenience stores and fuel stations. The filter, however, may also be used in applications other than fuel dispensers, such as being directly coupled to an engine.